Extremely Strange Issues with charging and battery on Zephyrus G14(GA401)

[DaLZy]

I have recently come into possession of a G14 that cannot detect or charge it's battery. Initially both windows and the bios agreed that the battery was on "0%" but the laptop was able to run without AC power. I was able to get the laptop to detect the true charge of the battery(26%) in windows for a moment but it wouldn't charge or update the percentage when the battery drained. I attempted a few more EC resets and battery reconnections and now the battery shows at 0% in bios and 100% in windows. Additionally the machine is extremely laggy when plugged into AC. When on ac power in the bios the moving icons freeze every few seconds and input is extremely delayed. In windows the laptop is super slow unless I unplug it. Battery voltage and stuff isn't detected in hwinfo64.

I suspect it's a cooked ec+charge controller but I don't know how to diagnose that since I'm new to this stuff. I need some pointers. I also can't get any components in until febuary due to chinese new year.

[pc_okay]

Hello,

Is the laptop slow too without battery? (Just charger plugged in)
Do you try with another working charger (with right amp) and maybe another battery.
You may try this first before messing with motheboard.

ps: Look at cpu frequency in task manager when lapyop is running slow.

[DaLZy]

Hello,

Is the laptop slow too without battery? (Just charger plugged in)
Do you try with another working charger (with right amp) and maybe another battery.
You may try this first before messing with motheboard.

ps: Look at cpu frequency in task manager when lapyop is running slow.

The first thing I tried was a new battery, didn't fix anything.

I don't have another barrel type charger, but type-c pd charging also doesn't work. I can try rigging up something with a 20v power supply and a barrel jack if I find one around the house.

Yes, looking in task manager the CPU is stuck at 400mHZ when plugged in. I haven't tried running with the battery unplugged but I suspect it won't change anything since it came to me with the battery unplugged and the previous owner described the same issues.

I suspect the last owner might have fallen victim to the metal latch when removing the battery and shorted out something on the board. Quite likely since he wasn't technically apt and replaced all the thermal pads/putty with thermal paste leading to no contact with the cooler...

[mon2]

Locate the 2 x DCin mosfets @ PQ8901 and PQ8902.

Remove all power. Meter in resistance mode.

Measure the resistance across the mosfet pins:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement. Repeat for PQ8902. Testing for a low resistance on each mosfet which means the mosfet is defective. Each measurement should be hundreds of k ohms or higher if the mosfet is ok.

[pc_okay]

Okay perfect.
Ater checking Mon mesurement, just check for missing component around battery connector.
Last time i see that, one guy teared out one little coil on the battery DATA line with his screwdriver. (i guess!)
So data line was open, and laptop was working on battery, but can't charge and remaining %% was crazy.

good luck !

[DaLZy]

Locate the 2 x DCin mosfets @ PQ8901 and PQ8902.

Remove all power. Meter in resistance mode.

Measure the resistance across the mosfet pins:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement. Repeat for PQ8902. Testing for a low resistance on each mosfet which means the mosfet is defective. Each measurement should be hundreds of k ohms or higher if the mosfet is ok.

pq8901:
s to d: 4.06 megaohm
s to g: 4.83 megaohm
g to d: 5.18 megaohm

pq8902:
s to d: 2.78 megaohm
s to g: 4.83 megaohm
g to d: 8.14 megaohm

seems like fets are ok? they are 2 different models

I had a look at the row of resistors pc_okay pointed out. Looks like they have already been tampered with by someone before me but all resistors are there.

The 2 resistors that were replaced read 2.7kohm, rest read 36kohm. But according to schematic they should all be 51kohm?

Edit: the two 2.7kohm resistors seem to be related to charger and battery temp sensing? this could be a explanation of strange behavior on charger, although it still doesn't explain why battery percentage isn't detected...

[mon2]

If the power adapter is under rated, the CPU speed will be throttled and the battery will not charge.

[DaLZy]

If the power adapter is under rated, the CPU speed will be throttled and the battery will not charge.

I am using the original 180w charger. I think the incorrect resistances may be causing the laptop to sense a abnormal battery connector and charge port temperature and throttle and stop charging.

[pc_okay]

If CPU throttle, please check PROCHOT# you need it to be high.
And more important (like you said) resistances i mentioned in post 5 are conneced to temperature sensor, thermistor look at PU9001, connected to resistance, connected to thermistor...
That can explain your throttle, replace this resistor with good ones.
You may see the charging problem after if it's not fixed.